Abstract
Hepatitis B virus (HBV) infection is a dynamic disease where patients progress through several stages defined by HBV e-antigen (HBeAg) status, HBV-DNA levels and transaminase elevations, with antiviral therapy indicated only in specific stages. However, some patients cannot be classified into one of the stages and are said to fall into an 'indeterminate phase' or 'grey zone'. Exact definitions of the indeterminate phase vary from guideline to guideline as a result of different cut-off values for biomarker measurements. Data suggest that as many as 50% of HBV patients may be in an indeterminate phase and may not rapidly transition out of this phase. Clinical data that suggest these patients are at increased risk of hepatocellular carcinoma (HCC) are complemented by molecular evidence of integrations of HBV-DNA into the host genome, chromosomal translocations and immune activation despite liver enzymes that may suggest lack of inflammation. Antiviral therapy reduces these hepatocarcinogenic mechanisms and is reflected in a reduction of fibrosis and HCC risk. We review key data on patients in the indeterminate phase, with emphasis on HCC as an outcome. We take a holistic approach and link new biological data with clinical observations as well as examine the potential role of antiviral therapy in reducing HCC risk among patients in the indeterminate phase. With the availability of safe and effective oral antivirals, consideration must be given as to how much residual risk of HCC should be tolerated among patients in the indeterminate phase.